1. Field of the Invention
The present invention generally relates to motion estimation, and more particularly to a method of block-based motion estimation adaptable to frame rate up conversion (FRUC).
2. Description of Related Art
Frame rate up conversion (FRUC) is commonly used in the digital image display of a device such as a digital TV to generate one or more interpolated frames between two original adjacent frames, such that the display frame rate may be increased, for example, from 60 Hz to 120 Hz or 240 Hz. The generation of the interpolated frame is typically performed by using an interpolation of motion compensation technique. Shown in FIG. 1 is an example of generating an interpolated frame according to a previous frame and a current frame. Specifically, according to the conventional technique, the motion of the macroblocks (MBs) in the current frame with respect to the corresponding MBs in the previous frame is first estimated. The interpolated frame is then interpolated based on the motion estimation. It is observed, however, that the interpolated blocks in the interpolated frame are generally generated in a random manner. Such randomness in time makes the display of the interpolated frame difficult or complicated, as the frames are mostly displayed regularly from left to right and from top to bottom. Moreover, the interpolated blocks are ordinarily not aligned with the division of the macroblocks of a video frame. As a result, the memory data access for processing the interpolated blocks becomes random and pixel-based, and thus incurs latency. Furthermore, the interpolated blocks may overlap each other. The overlapping further complicates the display of the interpolated frame. The pixel-based motion compensation may also affect the speed and accuracy of other process(es), such as occlusion handling, which typically need to be performed in a pixel-based manner as well.
For the reason that conventional frame rate up conversion suffers latency, complexity and inaccuracy, a need has arisen to propose a novel scheme in order to speed up and simplify the motion compensation in interpolating an interpolated frame, for example, in the frame rate up conversion.